1. Field of the Invention
The present invention relates to a non-volatile semiconductor storage device.
2. Description of the Related Art
Some semiconductor integrated circuits with a memory such as DRAM or SRAM and a logic circuit are required to store initial setting information in a non-volatile manner, such as recovery information on a defect memory cell and circuit setting information. To store the information, the semiconductor integrated circuit includes a non-volatile semiconductor storage device including a fuse element (see, for example, JP 2005-116003). One proposed non-volatile semiconductor storage device includes an insulating-layer destruction semiconductor memory element (hereinafter referred to as an e-fuse element). The e-fuse element stores information with a high voltage applied to the device to destruct an insulating layer, the high voltage being greater than the maximum rating of the device.
The non-volatile semiconductor storage device stores the initial setting information at a test stage in a manufacturing process. The storage device is requested to maintain the information for a long time after shipment. Depending on a fuse manufacturing condition and a programming condition, change with time after programming may destruct data of the storage device. The device is thus requested to have very high reliabilities.
Depending on the specifications of the non-volatile semiconductor storage device, it is hard to rescue a defect cell. A single bit fault may thus be a critical defect of the storage device.